US Patent Application Publication No. 2011/0142770 (Fletcher et al.) discloses sunscreen compositions comprising organic pigment particulates and methylcellulose. Also disclosed are methods of boosting the SPF (sun protection factor) and/or PPD (Persistent Pigment Darkening) of a sunscreen composition having organic pigment particulates. The methods involve including methylcellulose in the sunscreen composition.
U.S. Pat. No. 5,505,935 (Guerrero et al.) discloses a cosmetic sunscreen composition that includes an ethylene/vinyl acetate copolymer, an acrylic polymer such as poly(methyl methacrylate) and a chromophoric organic sunscreen agent capable of absorbing ultraviolet radiation within the range 290 to 400 nm. The ethylene/vinyl acetate copolymer and acrylic polymer were found to interactively boost the SPF value of the organic sunscreen.